A device for determining a flow characteristic, in particular flow velocity, of a fluid in a conduit, comprises a conduit body (110), at least four pairs of ultrasonic transducers (116, 118; 122, 124; 128, 130; 132, 1340 defining swirl sensitive acoustic paths (128, 130; 132, 134). The ultrasonic transducers are arranged such that they define paired acoustic paths. The device also comprises means (142, 144) for measuring the transit times of transmitted ultrasonic waves and for determining a flow characteristic from the measured transit times.